Now I want to calculate the max(Amount) and get the date of that maximum grouping by Group and Category.

And this is the problem:

If I do the group by with Group and Category, I don´t know in which date I had the maximum, the solution I thought is doing a link with the amount or with a key composed by Group&Category&Amount but I don´t think it would be the best solution, overall if there are repetead maximums.

And I can´t group by Group, Category and Date, because I want the maximum amount of those Dates and not the maximum per day.